Acoustic Deflector as Heat Sink

ABSTRACT

An omni-directional acoustic deflector includes an acoustically reflective body having a substantially conical outer surface, and an inner surface opposite the outer surface. The inner surface defines a region that is configured to be coupled to a first electronic component such that heat is transferred from the first electronic component to the outer surface of the acoustically reflective body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/475,542, filed Mar. 31, 2017, which is incorporated herein byreference in its entirety.

BACKGROUND

This disclosure relates to an acoustic deflector that also serves as aheat sink for heat dissipating electronic components.

SUMMARY

All examples and features mentioned below can be combined in anytechnically possible way.

In one aspect, an omni-directional acoustic deflector includes anacoustically reflective body having a substantially conical outersurface, and an inner surface opposite the outer surface. The innersurface defines a region that is configured to be coupled to a firstelectronic component such that heat is transferred from the firstelectronic component to the outer surface of the acoustically reflectivebody.

Implementations may include one of the following features, or anycombination thereof.

In some implementations, the acoustically reflective body is formed of amaterial having a thermal conductivity of 50 W/m-K or greater (e.g., 96W/m-K).

In certain implementations, the omni-directional acoustic deflectorincludes a plate that mounts to the acoustically reflective body to forman acoustic cavity therewith. The plate has an irregular surface.

In some examples, the plate mounts to the acoustically reflective bodyso as to form an acoustic seal therewith.

In certain examples, the irregular surface is arranged to accommodate asecond electronic component.

In some cases, the irregular surface includes a feature along a firstside of the plate that extends into the acoustic cavity.

In certain cases, the feature includes a bump that is arranged toaccommodate placement of a second electronic component along a secondside of the plate opposite the acoustic cavity.

In some implementations, the substantially conical outer surface isconfigured to be disposed adjacent an acoustically radiating surface ofan acoustic driver, and the acoustically reflective body has a truncatedconical shape that includes a top surface that is configured to becentered with respect to a motion axis of the acoustic driver. Theacoustically reflective body has an opening in the top surface thatextends into the acoustic cavity enabling acoustic energy from theacoustic driver to pass into the acoustic cavity.

In certain implementations, the inner surface of the acousticallyreflective body defines a projection that includes the region forcontacting the first electronic component.

In another aspect, a speaker system includes an acoustic enclosure; anacoustic driver coupled to the acoustic enclosure; circuitry forpowering the acoustic driver; and an omni-directional acousticdeflector. The omni-directional acoustic deflector includes anacoustically reflective body that has a substantially conical outersurface that is configured to be disposed adjacent an acousticallyradiating surface of the acoustic driver, and an inner surface oppositethe outer surface. The inner surface defines a region that is configuredto be coupled to a first electronic component of the circuitry, suchthat heat is transferred from the first electronic component to theouter surface of the acoustically reflective body.

Implementations may include one of the above and/or below features, orany combination thereof.

In some implementations, the speaker system includes a base that isconfigured to be coupled to the omni-directional acoustic deflector toform a compartment therebetween.

In certain implementations, the acoustically reflective body defines oneor mounting posts for mounting the base to the omni-directional acousticdeflector.

In some examples, the circuitry is disposed within the compartment.

In certain examples, the speaker system includes a battery pack disposedwithin the compartment for powering the circuitry.

In some cases, the base forms a watertight seal with theomni-directional acoustic deflector.

In certain cases, the omni-directional acoustic deflector includes aperipheral edge with a first taper and the base includes a peripheraledge with a second taper that is configured to mate with the first taperto form the acoustic seal.

In some implementations, the region is coupled to the first electroniccomponent via a thermal interface material.

In certain implementations, the thermal interface material has a thermalconductivity of at least 1 W/m-K (e.g., about 3 W/m-K).

In some examples, the thermal interface material is compressed betweenthe first electronic component and the acoustically reflective bodyabout 25% to about 75%.

In certain examples, the acoustic driver provides an alternating airflow along the outer surface of the omni-directional acoustic deflectorwhich contributes to forced convective cooling.

In some cases, the acoustic enclosure includes a pair of passiveradiators configured to be driven by acoustic energy provided by theacoustic driver such that the passive radiators are driven acousticallyin phase with each other and mechanically out of phase with each other,to minimize vibration of the acoustic enclosure.

In certain cases, the acoustically reflective body comprises a leg forcoupling the acoustically reflective body to the acoustic driver, suchthat the substantially conical outer surface is disposed adjacent to anacoustically radiating surface of the acoustic driver.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective and cross-sectional views, respectively,of a speaker system.

FIG. 2 is a perspective view of an acoustic assembly from the speakersystem of FIG. 1A.

FIG. 3 is a cross-sectional view of a deflector sub-assembly from theacoustic assembly of FIG. 2.

DETAILED DESCRIPTION

Multiple benefits are known for omni-directional speaker systems. Thesebenefits include a more spacious sound image when the speaker system isplaced near a boundary, such as a wall within a room, due toreflections. Another benefit is that the speaker system does not have tobe oriented in a particular direction to achieve optimum high frequencycoverage. This second advantage is highly desirable for mobile speakersystems where the speaker system and/or the listener may be moving.

This disclosure is based on the realization that a passive acousticcomponent (e.g., an acoustic deflector) of such an omni-directionalspeaker system could also serve another purpose as a heat sink forconducting heat away from a heat producing electronic component packagedwithin the speaker system. An alternating (a/c) air flow that isproduced via the normal operation of an acoustic driver can be used toprovide forced convective cooling for the passive acoustic component,thereby to further enhance heat transfer away from the heat producingelectronic component.

In the examples described below, an acoustic deflector forms an upperwall of a sealed volume that contains electronics and a battery package(e.g., a lithium-ion battery). The electronics can include heatproducing components, such as audio amplifiers and charge controlcircuitry for the battery package. This heat production can lead toundesirable thermal conditions in the sealed volume. Lithium-ionbatteries, in particular, are subject to a limited operating range andtherefore, heat is required to be efficiently transferred from thevolume in order to improve the thermal conditions therein.

By creating the acoustic deflector out of thermally conductive material,and placing the acoustic deflector in contact with the heat producingcomponent(s), the conduction of heat out of the enclosure volume isimproved. In addition, the deflector resides adjacent the acousticdriver which acts as a source of an alternating air flow thatcontributes to a cooling effect of the acoustic deflector.

FIGS. 1A and 1B are drawings showing a perspective view and across-sectional view, respectively, of a speaker system 100 thatincludes an outer housing 102 in the form of a substantially cylindricalsleeve, which houses an acoustic assembly 104, and a top cap 106 whichseals off a top end of the housing 102 and provides a physical userinterface 108. The housing 102 includes a plurality of perforationswhich allow acoustic energy from the acoustic assembly 104 to passtherethrough.

Referring to FIGS. 1B and 2, the acoustic assembly 104 is made up of anacoustic sub-assembly 110 and a deflector sub-assembly 112. The acousticsub-assembly 110 includes a single downward firing acoustic driver 114secured to a vertical acoustic enclosure 116. A pair of passiveradiators 118 are arranged on opposing side walls of the enclosure 116.The passive radiators 118 are configured to be driven by audio signalsfrom an audio source (not shown) such that the passive radiators 118 aredriven acoustically in phase with each other and mechanically out ofphase with each other, to minimize vibration of the enclosure 116.

The volume within the region above the acoustic driver 114 and insidethe enclosure 116, as “sealed” with the passive radiators 118, definesan acoustic chamber. The diaphragms of the passive radiators 118 aredriven by pressure changes within the acoustic chamber resulting fromoperation of the acoustic driver 114.

The deflector sub-assembly 112 includes an omni-directional acousticdeflector 120 and a bottom cap (a/k/a base 122), which are coupledtogether to form a compartment 124 that houses electronics, which powerthe speaker system 100. The electronics include a battery package 128,and a printed circuit board 130 that includes a plurality of electroniccomponents mounted thereto. The electronic components 130 include, amongother things, an amplifier chip and a battery charger chip. The batterypackage 128, however, may have a relatively low temperature limit. Forexample, in some cases, the battery package 128 has a temperature limitof about 52 degrees Celsius while charging and about 70 degree Celsiuswhen not charging. As discussed below, to assist heat transfer out ofthe compartment 124 to provide for more suitable thermal conditions forthe battery package 128, the acoustic deflector 120 can be formed from ahigh thermal conductivity material.

The omni-directional acoustic deflector 120 has four vertical legs 132(a/k/a “mounting pillars”) to which the enclosure 116 is mounted.Acoustic energy generated by the acoustic driver 114 propagates downwardand is deflected into a nominal horizontal direction by an acousticallyreflective body 134 of the acoustic deflector 120.

There are four substantially rectangular openings 136. Each opening 136is defined by the enclosure 116, the acoustic deflector 120 and a pairof the vertical legs 132. These four openings 136 are acoustic apertureswhich pass the horizontally propagating acoustic energy. It should beunderstood that the propagation of the acoustic energy in a givendirection includes a spreading of the propagating acoustic energy, forexample, due to diffraction.

The illustrated acoustic deflector 120 has a nominal truncated conicalshape that is configured to be centered (i.e., coaxial) with respect tothe motion axis of the acoustic driver 114. In other examples, the slopeof the conical outer surface between the base and vertex of the cone(a/k/a “cone axis”) is not constant. For example, the outer surface mayhave a non-linear slant profile such as a parabolic profile or a profiledescribed by a truncated hyperboloid of revolution. Notably, the body ofthe acoustic deflector 120 is made of a thermally conductive material(e.g., a material having a thermal conductivity of at least 50 W/m-K),such as a metal. In some cases, the body is formed of cast aluminumA380, which has a thermal conductivity of 96 W/m-K).

Referring to FIG. 3, an inner surface of the body 134 defines one ormore projections 200 (one shown) for contacting, either directly orindirectly, one or more of the heat dissipating electronic components(e.g., the amplifier chip and/or the battery charger chip) such thatheat is transferred from the electronic component(s) to the outersurface of the acoustically reflective body 134. In the illustratedimplementation, the projection 200 is coupled to a first electroniccomponent 202 via a thermal interface material (e.g., a thermallyconductive pad 204). In some cases, the thermally conductive pad 204 isformed of a compressible thermally conductive material. The use of acompressible material helps to accommodate dimensional tolerances tohelp eliminate air gaps. In some cases, the thermal interface materialis compressed between the first electronic component 202 and theacoustically reflective body 134 about 25% to about 75%. Preferably, thethermally conductive pad 204 has a thermal conductivity of at leastabout 1 W/m-K, and, preferably, at least about 3 W/m-K. Suitable thermalpads are available from Parker Chomerics, Woburn, Mass., under the tradename THERM-A-GAP™ Thermally Conductive Gap Filler Pads.

Heat is conducted away from the electronic component(s) (e.g., the firstelectronic component 202) to the outer surface of the acousticallyreflective body 134. The normal operation of the acoustic driver 114provides an alternating (a/c) air flow along the outer surface whichcontributes to convective cooling of the acoustically reflective body134. Through this convective and conductive heat transfer, sufficientheat is removed from the compartment 124 to provide suitable thermalconditions for the battery package 128.

Referring still to FIG. 3, a plate 206 is mounted to the acousticallyreflective body 134 (e.g., via thread forming screws) to form anacoustic cavity 208 therewith. A gasket material can be provided at theinterface between the plate 206 and the acoustically reflective body 134to help ensure an air tight seal.

An opening 210 is provided in the top surface of the acousticallyreflective body 134. The opening 210 extends into the acoustic cavity208, thereby allowing acoustic energy from the acoustic driver 114 (FIG.1B) to pass into the acoustic cavity 208. An acoustically absorbingmaterial 212 is disposed in the opening. This acoustically absorbingmaterial 212 attenuates the acoustic energy present near and at the peakof the lowest order circularly symmetric resonance mode. In someimplementations, the diameter of the opening 210 is chosen so that theresulting attenuation of the acoustic energy propagating from theacoustic driver 114 (FIG. 1B) is limited to an acceptable level whileachieving a desirable level of smoothing of the acoustic spectrum.

Notably, the plate 206 includes a bump 214 that is arranged toaccommodate placement of one or more relatively tall components (e.g., acapacitor 216) on the printed circuit board 130. The bump 214 alsoprovides an irregular surface within the acoustic cavity 208. Thisirregular surface can further help to break up certain acoustic standingwaves.

In some implementations, the base 122 is a two shot molded plastic partand includes an inner bowl 218 that is molded from a polycarbonate(PC)/ABS; and an outer layer 220 formed of thermoplastic polyurethane(TPU). The base 122 provides the main support for the battery package128 and printed circuit board 130. In that regard, the printed circuitboard 130 is secured to the battery package 128 (e.g., with screws) toform an electronic sub-assembly. That electronic sub-assembly is thensecured to the base 122 (e.g., with screws). The base 122 is thensecured to bosses 222 formed in the acoustically reflective body 134with thread forming screws. The base 122 includes a tapered peripheraledge 224, which engages a mating tapered edge 226 on the acousticallyreflective body 134 to form a watertight seal. The TPU outer layer 220on the base 122 helps to provide for a very tight seal with the acousticdeflector 120. This seal is helpful to protect the electronics againstmoisture, but it also keeps the heat trapped in the compartment 124, sothe conductive acoustic deflector 120 becomes an instrumental componentto the thermal cooling design.

The electronics 126 can be electrically connected to the acoustic driver114 (FIG. 1B) and the user interface 108 (FIG. 1A) via wiring, which maypass through one or more apertures in the acoustically reflective body134 and/or the acoustic enclosure 116. Grommets can be used to provide aseal between the wiring and the apertures.

A number of implementations have been described. Nevertheless, it willbe understood that additional modifications may be made withoutdeparting from the scope of the inventive concepts described herein,and, accordingly, other implementations are within the scope of thefollowing claims.

What is claimed is:
 1. An omni-directional acoustic deflectorcomprising: an acoustically reflective body having a substantiallyconical outer surface, and an inner surface opposite the outer surface,wherein the inner surface defines a region that is configured to becoupled to a first electronic component such that heat is transferredfrom the first electronic component to the outer surface of theacoustically reflective body.
 2. The omni-directional acoustic deflectorof claim 1, wherein the acoustically reflective body is formed of amaterial having a thermal conductivity of 50 W/m-k or greater.
 3. Theomni-directional acoustic deflector of claim 1, further comprising aplate that mounts to the acoustically reflective body to form anacoustic cavity therewith, the plate having an irregular surface.
 4. Theomni-directional acoustic deflector of claim 3, wherein the plate mountsto the acoustically reflective body so as to form an acoustic sealtherewith.
 5. The omni-directional acoustic deflector of claim 3,wherein the irregular surface is arranged to accommodate a secondelectronic component.
 6. The omni-directional acoustic deflector ofclaim 3, wherein the irregular surface includes a feature along a firstside of the plate that extends into the acoustic cavity.
 7. Theomni-directional acoustic deflector of claim 6, wherein the featurecomprises a bump that is arranged to accommodate placement of a secondelectronic component along a second side of the plate opposite theacoustic cavity.
 8. The omni-directional acoustic deflector of claim 1,wherein the inner surface of the acoustically reflective body defines aprojection that includes the region for contacting the first electroniccomponent.
 9. A speaker system comprising: an acoustic enclosure; anacoustic driver coupled to the acoustic enclosure; circuitry forpowering the acoustic driver, the circuitry comprising a firstelectronic component; and an omni-directional acoustic deflectorcomprising an acoustically reflective body having a substantiallyconical outer surface configured to be disposed adjacent an acousticallyradiating surface of the acoustic driver, and an inner surface oppositethe outer surface, wherein the inner surface defines a region that isconfigured to be coupled to the first electronic component, such thatheat is transferred from the first electronic component to the outersurface of the acoustically reflective body.
 10. The speaker system ofclaim 9, further comprising a base configured to be coupled to theomni-directional acoustic deflector to form a compartment therebetween.11. The speaker system of claim 10, wherein the acoustically reflectivebody defines one or mounting posts for mounting the base to theomni-directional acoustic deflector.
 12. The speaker system of claim 10,wherein the circuitry is disposed within the compartment.
 13. Thespeaker system of claim 10, further comprising a battery pack disposedwithin the compartment for powering the circuitry.
 14. The speakersystem of claim 10, wherein the base forms a watertight seal with theomni-directional acoustic deflector.
 15. The speaker system of claim 9,wherein the acoustically reflective body is formed of a material havinga thermal conductivity of 50 W/m-K or greater.
 16. The speaker system ofclaim 9, wherein the region is coupled to the first electronic componentvia a thermal interface material.
 17. The speaker system of claim 9,wherein the acoustic driver provides an alternating air flow along theouter surface of the omni-directional acoustic deflector whichcontributes to forced convective cooling.
 18. The speaker system ofclaim 9, wherein the acoustic enclosure comprises a pair of passiveradiators configured to be driven by acoustic energy provided by theacoustic driver such that the passive radiators are driven acousticallyin phase with each other and mechanically out of phase with each other,to minimize vibration of the acoustic enclosure.
 19. The speaker systemof claim 9, further comprising a plate that mounts to the acousticallyreflective body to form an acoustic cavity therewith, the plate havingan irregular surface.
 20. The speaker system of claim 9, wherein theacoustically reflective body comprises a leg for coupling theacoustically reflective body to the acoustic driver, such that thesubstantially conical outer surface is disposed adjacent to anacoustically radiating surface of the acoustic driver.